Description

Our HBase pal/guru Gary Helmling was kind enough to do a code review of HBaseStorage. He suggested some good filter optimizations:

when using the "lt*" and "gt*" options, set the start/stop rows on the Scan instance, at least in addition to the RowFilters. Without this you're doing a full table scan, regardless of the RowFilters.

when selecting specific columns or entire families to return, it would be more efficient to set the family + columns on the Scan object (addFamily(), addColumn()), instead of using a FilterList. I'm not familiar with the family:prefix handling you mention, but that would still seem to require filters. But if that's not being used, it would be better to avoid the FilterList for columns. At minimum, we should probably call Scan.addFamily() with the distinct families, so we can skip entire column families that are not being used. In the case of a table with 4 CFs, if, say, only 1 is being used, this could be a big gain.

We uncovered a significant performance problem with HBaseStorage > 0.9 when used with a long list of columns on a tall table. The previous use of filters is too hard hitting on HBase and it pegs HBase cluster CPU. We should consider this patch to be included in Pig 0.11.

Bill Graham
added a comment - 15/Nov/12 05:20 We uncovered a significant performance problem with HBaseStorage > 0.9 when used with a long list of columns on a tall table. The previous use of filters is too hard hitting on HBase and it pegs HBase cluster CPU. We should consider this patch to be included in Pig 0.11.

Initialization happens in the setLocation method often, since that's the first time the class has a conf object on the cluster. That can happen elsewhere in the initialization process though if it works.

Bill Graham
added a comment - 08/Nov/12 17:49 Initialization happens in the setLocation method often, since that's the first time the class has a conf object on the cluster. That can happen elsewhere in the initialization process though if it works.

Regarding your first issue you're totally right. It seems weird that it was implemented with filters at all.
The second issue is different. In HBaseStorage.setLocation those Families are added to the scan object. I don't understand why it's done there though.

Christoph Bauer
added a comment - 08/Nov/12 14:47 I'm starting on a patch for HBase Storage here at my company.
Regarding your first issue you're totally right. It seems weird that it was implemented with filters at all.
The second issue is different. In HBaseStorage.setLocation those Families are added to the scan object. I don't understand why it's done there though.